1. Field of the Invention
The present invention relates generally to optical scanners and, more particularly, to a system and method for decoding marks on a response sheet.
2. Description of Related Art
Elections, academic tests, referendums, surveys, gambling schemes, and other endeavors require the accurate analysis of marks made on response sheets. Optical scanners are typically used for this task to increase speed and accuracy. Such scanners obtain am image of the response sheet and analyze predetermined response areas to determine if a user has selected or marked the response areas. However, the image of the response sheet may include some amount of skew and/or distortion, which may occur for a variety of reasons. For example, the image of a response sheet may be skewed if the response sheet does not move straight though the transport system of the optical scanner. This can occur, for example, in cases where the optical scanner is designed to accommodate a variance in the size of the response sheets. Distortion can be caused by misalignment of the image scanner, printing errors (e.g., a response sheet being printed too light, too dark, blurry, or smudged), and dirty or imprecise scanners. These inconsistencies in the images of the response sheets can cause the optical scanners to incorrectly locate and interpret the responses areas on the response sheet so as to record a response area as marked when it is blank/unmarked and vice versa.